Automatic telephone system.



B. G. DUN HAM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909.

Patented July 14, 1914.

9 SHEETS-SHEET 1.

5111mm for B. G. DUNHAM. AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED JULY 12, 1909.

Patented July 14,1914,

9 SHEETS-SHEET 2.

B. G. DUNHAM, AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909.

Patented July 14,1914.

9 SHEETSSHEET 3.

B-. G. DUNHAM.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909.

1 1 0.3, 572. Pate'nte'd July 14, 1914.

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APPLICATION FILED JULY 12, 1909. 1 1 Q3,572 Patented July 14, 1914.

9 SHEETS-SHEBT 5.

1/95 in cows B. G. DUNHAM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909. 1, 1 03,572. Patented July 14, 1914.

9 SHEETS SHEET 6.

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B. G. DURHAM.

AUTdMATIG TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909.

1,103,572 Patented Jul 14,1914.

\ qv umm I 1 I W1 a r acmw a' B. G. D'UNHAM. AUTOMATIC TELEPHONE. SYSTEM.

APPLICATION nun JULY 12, 1909.

1,103,572. Patented July 14, 1914.1

B. G. DUNHAM.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 12, 1909.

Patented Juiy 14, 1914.

9 SHEETS-SHEET 9.

Gttomu a ephone Systems, of which thefollowing is a i s rA'rns P i FTQ.

BERT s. DUNI-IAM, or URBANA, onto, ASSIGNOR, BY. MESNE ASSIGNMENTS, TO

I wnsrnnn nnncrmc COMPANY, rumors. i

To all whom it may concern ,Be it known that I, BERT G. DUNHAM, av citizen of the United States, residing at Urbanayin the county of Champaign and State of Ohio, have invented certain new and useful Improvements in Automatic Telspecification.

' My invention relates to automatic telephonesystems andparticularly to those sysl tems in which a plurality of finder switches less than the number of subscribers are used 2 with a means for connecting the finder j switches through various other switches, 1

such as first and second selector and connector switches, to establish talking circuits between different subscribers.

' .The object of my invention primarily is to so arrange the circuits and switches that the number of switches employed may be varied to suit the volume of business rather than the total number of subscribers. In 5 systems, as usually employed, it is the prac-v tice toarrange a certain definite number of switches with trunking facilities based upon the total number of subscribers employed.

But by my system I am enabled to arrange I the subscribers in groups and to provide trunks extending from the different classes 1 of switches, so that the number of switches 5 in a group or the number of trunks em- 1 pl'oyed may be varied according to the num ber of I groups or in certain groups.

My invention consists in the various con- 1 be at any point removed therefrom. Fig. 2

structions, clrcuits and combinations of parts hereinafter more fully described and the claims.

to finderswitches less in number. than the total number of subscribers, generally about l the switch finds the subscribers line.

ten per cent. or five switches "to fifty subscribers. The. method of operating the finder switches is that employed in what is known as the Lattig & Goodrum system in which, by the operation of a line relay which occurs upon the closing of a subscribers circuit by removingthe telephone from the hook, the finder switches are automatically started and continue to operate until This also automatically cuts through the subcalls which would originate in the NEW YORK, N. Y., A CORPORATION 0F 1 AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent. Patentgd July 14 1914,, Application filed. July 12, 1909. Serial No. 507,195. b

l scribers line from the finder switch to a seilector switch or, in case of a large exchange, to what would be known as a first selector 1 switch. At this point my system varies ma- 5 terially from the systems heretofore em-' l ployed, in this, that it has been the custom heretofore in systems, such as described and in which flat or one-movement switches are used, to employ a second set 1 of finder switches to find the trunk selected by the firstselectorand these second finder switches would be connected to a second selector or connector switch, "as the case might be, while in my system I do'away with the second l finders and have the selector switches stepped up to a predetermined point to find 7 a group of subscribers and then automatically find an idle trunk in that group, so 1 that the selector switches partake of the nature of finder switches and selector switches having the capacity to be operated by impulses received from the subscribers stations through the finder switches to select a certain group and to then automatically find an idle trunk in that group after the impulses have ceased.

There are other features of the invention which will more fully appear in the detailed descriptions, which are as follows:

In the drawings, Figure 1 illustrates in diagram two subscribers"stations with the line and cut ofl? relays pertaining to these stations, these line and cut-off relays, it will be understood, will be ordinarily at the exchange while the subscribers stations will shows a finder switch, the circuits from the subscribers stations and from the line and cut-ofi'relays being shown connected to this switch, it being understood that such circuits would be connected in multiple to all the switches assigned to this group of subi scribers; that is, in the case of five switches to fifty lines, these subscribers lines would be in multiple to five switches. Fig. 3 shows what is generally known as a selector switch, but which, in this case, partakes of l the nature ofa selector anda finder switch, inasmuch as it selects the desired group of 1 trunks leading to the subsequent switches j and automatically finds an idle trunk in this 5 group. Fig. 4; is a second selector which i may or may not be employed, which per i lector, the constructions and arrangements being substantiall the same except so far as they are modi ed to provide for the release of the switches. Fig. 5 shows a con nector switch which could be connected to a second selector or a first selector; shows the ringing switch. Fig, 6 represents two stations which, in the description hereinafter, will be known as called stations. Fig. 7 is a diagrammatic view showing the arrangement of the trunking scheme between the various switches. Fig. 8 is a diagrammatic view of the same showing the parts in different positions and connections. Fig. 9 is a plan view of the switch which I preferably employ in connection with these circuits. Fig. 10 is a sectional elevation of the same on the line as m in Fig. 9. Fig. 11

is a sectional view on the line y y in Fig. 9

with the wipers moved over to the position 7 shown in dotted lines in Fig. 9. Figs. 12

and 13 are detail views of the release mechanism for the switch.

The arrangement of the drawings is as followspSheet 1 and Fig, l is adapted to fit onto Fig. 2; that is to say, if Fig. 1 is placed at the .right of Fig. 2 the connections between the parts in Fig. l and Fig. 2 will coincide. The same is true of Figs. 2' and 3.

Fig. 3 connects with Fig. 4, but, in this case, the lines are not extended as the trunks from the first selector of Fig. 3 would go to a number of second selectors, shown in Fig. 4, but one set of trunks leading from the top of Fig. 3 would connect with a set of trunks coming up from the bottom of Fig. 4. Fig. 4 will oin onto Fig. 5 and Fig, 5 will join onto Fig. 6. Figs. 7 and 8, being more general in their nature and relating to the general plan of the switches, are complete in themselves. The drawings on Sheet 9, and including Figs. 9 to 13, are difierent views showing the general style of switches used, the-switches being all practically the same in their general construction and operation and differing in their association, in different cases, with different relays for adapting them to the positions they occupy in the systems and functions which they perform.

As stated above, the switches are arranged in groups, each group of finders being adapted to handle 50 lines and each group of selectors being adapted to handle as many groups of trunks leading to the other selectors or connectors as the volume of business demands. For illustrating purposes I have considered 'each selector as handling ten grou s of four trunks each, each group of trun s being separated by a set of dead contacts. It w1ll be understood that all of the switches-have several banks of contacts, the finders and selectors having preferably four such banks of contacts, one

above the other, the corresponding contacts in the banks, which handle the line and mate Fig. 5.

up the outgoing "calls.

from the respective subscribers and the other two contacts handling the local circuits for operating the switches, being arranged in vertical lines. The switches are provided with an equal number of wipers to travel over these banks, which I preferably arrange one above the other on a vertical shaft, as shown in Figs. 10 and 11, which represent a connector switch and shows only three such banks and wipers. In Fig. 2, which shows the finder switch, I have shown five sets of contacts representin five difierent subscribers lines and these vesets of contacts might be considered as representing one set of contacts out of each lglroup of ten, making up the five groups of fty contacts in the switch. It will be understood that there would be in a full-sized switch in this system, nine other sets of contacts in each group and these contacts would be multiplied to each ofthe five switches which constitute the roup of finder switches assigned to fifty hues. I

In Fig. 3, which represents the first select-or, I have also shown five sets of contacts, the middle set being, as indicated, blank or dead; that is, they have no circuits connected to them. These sets of contacts,

therefore, would represent two groups of trunks of two trunks each, it being: under.

stood that these groups might each contain any desired number of trunks, each group being separated, as above described, by a set of dead contacts. Each group of trunks from these contacts in Fig.- 3, which represents the first selector, would lead to a group of second selectors to which they would be connected in multiple or to a group of connectors to which they would be connected in multiple, whether or not the second selectors are used depending upon the ultimate capacity of the exchange. I

Fig. 4, which represents the second selectors, is, in this respect,- substantially the same as Fig. 3; that is, it represents as connected to a switch two groups of connectors of two trunks each, the trunks in this case leading to a corresponding number of groups of connector switches. lesser number of contacts associated with these dilferent switches to avoid complicatloii since, as before stated, each of the switches would normally have fifty sets of,

contacts divided into as many groups as deslred to accommodate the traffic.

Flg. 5, wh1ch represents the connector switch, shows only two sets of contacts which lead out to the subscribers and .take These two sets of contacts represent the contacts from two subscribers lines out-of a group of fifty, which this connector switch will serve, it

being understood that these contacts would be multiplied together 'connector switches, the number of connector switches so used I have shown the I being dependent upon the amount of traffic passing through the exchange of which this is a part. 7

Fig. 7 illustrates the arrangement of the multiple connections of the subscribers lines to the finder switches and connector switches and the multiple connections of the trunks between the selector switches and from the selector to the connector switches. In this case two finder switches, both of the same group, are represented as being connected to different first selector switches. Each of these first selector switches being adapted to connect to either one of two groups of second selectors, only one group of second selectors of two each being shown. Then this group of second selectors of two switches is adapted to connect with two groups of connectors of two switches each.

Fig. 8 shows three finder switches rep= resenting three groups. These finder switches are connected to three first selector switches and these selector switches are connected in multiple, the bank contacts being arranged in groups of two trunks each, these trunks connecting in multiple to second selector switches arranged in groups. Two groups of trunks are shown for each first'selector which trunks would normally lead to four different second selectors, two only, however, being shown. The second selectors also each show two groups of two trunks each, which trunks are connected in multiple to four connector switches. The bank contacts of these connector switches being so connected in multiple to the bank contacts of the finder switches.

With this primary description of the drawings it is thought that the circuits and the operation of the device would probably be best understood by describing the operation of the different parts necessary to connect a called subscriber with a calling subscriber.

Starting with Fig. 1, I assume that station A is to connect with station A in Fig. 6. Each. subscribers station would be provided with the usual talking and signaling instruments, a representing the receiver, a the switch hook, a one of the contacts in the switch hook, c and c the windings of the induction coil, 3 the transmitter, b an impulse transmitter, b and b springs and contacts for opening the circuit by the movement of the impulse transmitter. In originating a call, subscriber A'removes his receiver, a, from hook, M, which alloWS said hook toclose against the contact, a and we get the following circuit: from contact a by wire 1, contacts 6 and 6 wire 2, transmitter 3, winding 0 of induction coil 0, wires 4, 5 and 6, springs 06 and d of relay D, wire 7, coil 6 of relay E, wire 8, battery 00, wires 10 and 11, coil 6 wire 12, springsd and d of relay D, lines I 13 and 14, to hook 11 at the subscribers station, thus completing the battery circuit through relay E, which energizes the said relay E and causes spring, 6 to make contact with e and break contact with .6

When relay E is not energized we have a normally open circuit from ground 2,

through wires 16 and 17, springs a and 6, wire 18, to contact a, in Fig. 2. This is the ground connection that causes the finder switch to rotate past the terminal contacts of subscribers lines whose receivers are in normal portions on the telephone hook. The energizing of the relay E closes the following circuit which starts the finder switch starting with ground a, Fig. 1, throughwires 16 and 17, spring a contact 6, wire 19, spring I), contact b, of the finder switch B (Fig.2) wire 20, contact 0*, spring 0 wire 21, through relay D wire 22, to battery m wire 23, to ground 2 thus completing the circuit to energize the relay D At the same time, relay E is energized over a branch circuit from wire 20, to wires 25 and- 26, through relay E to battery wflto ground 2 thus energizing relay E The energizing of relay E causes the armature spring 6", to engage contact, 6, which closes a circuit from ground 2 through spring e, contact e, wires 27 and 28 to relay F and battery 90 to ground 2 t us energizing relay F. The purpose of relay F is, when ener- I gized, to hold the line wires 46 and 49 and the starter wire 19 open until the switch stops rotating. This latter is accomplished ture, at, will contact with d and thus close I a circuit from ground 2 through wire 30, spring (Z contact 0?, wire 31, motor magnet C, battery a to ground 2 This energizes the motor magnet C and causes it to operate its armature preparatory to moving the wipers, a, a9, a and a, of the finder switch into engagement with the contacts, a, a, a and a. As soon as the motor magnet, C, is energized, its armature spring, 0 is withdrawn from contacts, c ,thus opening the circuit that energizes relay D The deiinergizing of rela Dtwill open the circuit that energized t e motor magnet C and the wipers, a, a a" and a, will be moved forward one step. If the line 'relav of asubscribers line, which is connected to this by energizing relay G by the operation of reset of terminals, has not been operated, the

' contact or terminal, a, would be grounded and the wipers, being stepped up one step through the agency of the starter wire, as described, would cause the wiper, a, to find ground on the terminal, a, which would cause the relay, E to" get current from wiper, a, Wire 32, spring e contact 6*, wire 26, relay E battery m ground 2 The relay D will also be supplied with current from wiper a, wire 32, contact a spring 'e, wire 25, contact 0*, spring 0 wire 21, re-

lay D, wire 22, battery (/0 wire 23, to ground 2 This will cause the motor magnet, O, to again become energized which will in turn, deenergize relay D and cause the switch to make another step, this operation being continued so long as the wiper, a

contacts with a grounded terminal over the following circuit, ground on wiper (L28, wire 32, contact s rings e and 6, wire 26 through the re ay E battery X and groundat 2 The switch is now stepped up two steps and wiper, a, has engaged contact, 0, from which the ground has beenremoved by the operation of the line relay E, and the relay Ebecornes deenergized and the switch stops rotating as the deenergizing of this relay breaks the motor magnet circuit, so that it can no longer receive current. The switch having stopped rotating with the wiper, 0?", upon the contact, a, a circuit is closed through the cut-ofi relay D (Fig. 1) as fol lows: ground 2, spring a, contact a", wire 33, wiper a, contact a, wire 34,'relay D, Wires and 10, battery m, wire 16, and to groundz. This energizes the relay D (Fig. 1) and cuts out the line relay E from the subscribers line, which is extended to the wipers, a and a with the line relay removed therefrom. The finder switch has now found the subscribers lines which are extended by the relay F and are cut through 1 to line wipers, (L33 and a, of thefirst selector switch S over the following circuit: wipers a and a wires and 45, springs f and f, armatures f and f wires 49 and 46, armatures a and 6 contacts a and 7), wires 89 and 86, to wipers a and at. These wipers would now be ready to connect with the terminalsv of a trunk leading to a second selector or a connector, but, inasmuch as these wipers may have to pass over some contacts or terminals of'lines which are in I use or busy, provisionis made for breaking the connection between the wipers of the finder switch and the wipers of the first selector, while the switch is being operated. This is accomplished as follows: The moving of the finder switch has shifted ofi'-normal switch, 6 to contact, 6 thus closing B and B are thus both energized and,-in operating their armature springs, break the line circuit to the wipers, as above described, and close the lines to the operating relay, 0 over the following circuit: springs b and a, contacts 6 and a1, wires 47 and 48, coils c and c of relay G battery .2, the line being closed at the subscribers station and cut through to the springs I) and a, as before described, battery 2 would be in-, cluded in the circuit thus closed through the rela C and energizing the said relay.

T e energizing of. relay C causes it to close its armature spring 0, against contact 0 and break the contact at c". The closing of the spring, 0', against the contact 0 gives us the following circuit: from ground a, wire 52, spring f contact f, wire 53, contact 6 spring 6 wire 54, spring 0 contact 0 wires 55 and 56, to relay D battery m and ground 2 also through wire 58, to relay E battery w and ground 2 so that both of the relays D and E are energized. The relays, D and Eflare both slow relays; that is, they are not deenergized readily, but will. hold their magnetism for an appreciable amount of time, so that impulses of current through them will keep the armatures held up, while the relay, C1 being a normal relay, will respond to any impulses of current and attract and repel its armature spring by impulses of current passing therethrough. The first selector switch, S, is now ready to receive impulses from the impulse transmitter, b, offthe calling subscriber, which is arranged to break the closed circuit now existing on the subscribers line through the first selector operating relay, C and battery, 2. Each time this circuit is broken the armature spring,

c of this operating relay O is released w ich would break the circuit through the slow relays, D and E at contact 0 but these relays being slow would maintain their magnetism and hold up their armatures for an appreciable time and until the relay, 0 gets another impulse in the event that the impulses followed in ordinaril rapid succession. The contacting of t e armature spring, a, of the operating rela G with back contact, a, closes a circuit t rough the motor magnet, G, of the selector switch. This motor magnet, G is arranged, when energized, to draw up its armature against the tension of a spring and retract the operating pawl for the switch one notch, the mechanical construction being more particularly described hereinafter in connection with Fig. 9. As the motor magnet, G is deenergized the spring retracts the armature and also pushes the pawl forward,-thus moving the switch one notch or step. The

circuit for energizing this motor magnet, G may now be traced as follows: from ground a, wire 52, spring f, contact f,

. contact 0",

wire 53, contact 6, spring 6 wire 54, spring 0", contact 0, wires 59 and 60, motor magnet G wires 61 and 62, contact a, spring e f, battery m, to ground .2. The immediate closing of the subscribers line through relay C would reenergize the relay C and by attracting its armature, circuitof the motor magnet G would be .opened which would become deenergized and thus give the switch its initial movement of one step forward. This first step of the selector switch, S, would allow the off-normal spring, a, to break the contact, a, through which current is being supplied to the holding relays B and B which, if

allowed to be deenergized, would break the line circuit through the operating magnet To prevent this, relay H is provided which is energized at the same time that the motor magnet G becomes energizedby the closing of the armature spring, 0 against over the following circuit: from ground a, wire 52, spring f contact 1, wire 53, contact 72 spring b wire 54, spring 0', contact 0, wire 59, wire 63, w1re 64, wire 65, spring f, contact f, wire 66,

relay H, wire 67 wire 62, contact 6 spring 6 battery m", to ground 2 The relay H is a slow relay and will hold over during the impulses transmitted to motor magnet G The energizing of the'relay H will close a shunt around the open contact, a, from wire 38, contact h spring h wire 67 to wire 40, which allows the relays B and B to find ground over the switch wire 38, as before described.

Now, assume that the called subscriber with whom the calling subscriber A desires connection is in the second group of second selector switches. This would be in the set I of contacts at the right of the dead contacts at 8 Assuming, as shown in the drawings, that there are only two trunks in each group, i-t would be necessary for the calling subscriber to transmit four; impulses over the line to step the first selector switch over the two trunks in the first group, the dead contacts, s and into the first set of-contacts be-' longing to the first trunk in the second group. The calling subscriber, therefore,

' turns his impulse transmitter four notches or steps, which transmits four impulses through the operating relay 0, which, in turn, transmitsfour impulses through the motor magnet Gflwhich steps up the wipers,

00 ,4 c0 and a until they rest upon the contacts, a), a, a and a, of the first trunk in the second group. The impulses now cease with the line closed at the subscribers station. The operatingmagnet, C is still energized, but the motor magnet, G and the slow relay, H, are deenergized. In case the first trunk is busy, thecontact, a, will be grounded in the manner her i after described, by the action of the first selector switch, which is using this trunk, and the wiper, a therefore, will be grounded through this terminal and the selector switch, S will continue to operate until it finds an 1dle trunk, in the followin manner: The deenergizing of the slow re ay, H, has broken the shunt from the switching wire 38, which was holding energized the relays B and B, and means are therefore provided for reenergizing these relays over the following circuit: from ground at terminal a wiper a, wire 69, spring (1 contact wire 70, spring k contact h", wire 71,'contact it spring h, wire 67, wires 41, 42, 43 and 44, through relays B and 13?, batteries a and w, to ground 2 and a. The circuit thus traced divides on wire at h and passes through wire 72, contact h spring k wire 73, spring a, contact a", wire 74, contact 9 spring 9 wire 77, relay K, battery 50 and ground 2 This energizes the relay operating relay for the automatic stepper. The energizing of the relay, K, gives us the following circuit over the motor magnet G ground .2 wire 78, contact 70 spring 7%, wire 79, wire'63, wire 60, motor magnet G wires 61 and 62, contact 6 spring a, battery m", and ground a. This energizes the motor magnet, G and causes the switch operating pawl to move back one step preparatory to stepping the switch forward when the motor magnet, G is deenergized. The circuit for the operating relay K, it will .be noticed, passes through the contacts 9 and motor magnet armature spring 9 so that, as soon as the motor magnet is energized, it disconnects the operating relay K, which in turn deenergizes the motor magnet, G and causes it'to move the switch forward one step. This operation will continue so long as the wiper, a, would find a grounded contact in the set of trunk contacts leading to the second selector switches.

We will assume that the contacts, 8 be long to an idle trunk and the wiper, at, does not find ground and hence the selector switch stops at this point. Inasmuch as the relays B and B are held up through the ground on the wiper, a these relays will be deenergized when the wipers have reached an idle trunk, the deenergizing'of the relays B and B will open the line wires through relay C and switch them onto the wipers, a and a, as before described. The deenergizing of relay C will cause the slow K, which may be termed the p relays D and E to become deenergized and The number of trunks and each group are generally arranged in multiples of or, if more trunks are needed, in multiples of 10, in the first case then the movement of the dial to come into the dif- 5 ferent groups would be 5, 10, 15, etc., and in the other case it would be 10, 20, '30, etc. Any desired arrangement can be made, however, and an arbitrary arrangement of num bers in calling may be used.

To provide against the possibility of the selector switch stopping on a busy trunk, in

which energizes the magnet K from the contact 9 wire 75, relay F battery as, ground 2 This causes the armature spring f to engage with contact, f, and closes the circuit through wires 57 56 and 58, through the slow relays D and E batteries :0 and w", to ground a and 2 so that eventhough the calling subscriber should hang up and thus open his line, the switch would continue to step over the busy trunks until an idle trunk or ungrounded terminal was found. This relay, F is dependent for its battery supply by reason of its connection to the ,wiper, a and, in the event that the wiper stops on an ungrounded connection, this relay, F will also be denergized and will drop back to normal position. The linesare now out through to the second selector switch of the second group. The denergizing of the relay D permits its armature spring, al to contact with the back contact, 03, which closes a grounded connection from ground .2", contact al spring 0Z wire 69, wiper a, thus putting ground on a of the set of contacts, 8 thus rendering this trunk busy to all other selector switches. The terminal, a, is connected by wire 80 to the offnormal spring, a, of the second selector, S and inasmuch as the operation of the second selector, so far as the stepping around and finding a trunk is concerned, is identical with the first selector, S the parts are letteredthe same and the operation will be the same, the only difierence being in the operation of the release which will be more fully described hereinafter in connection with the releasing of all the switches.

Assuming that the party desired is in the first group of connector switches and that the first trunk is idle, the second selector, S will be stepped up one step and its wiper, a, not finding ground, the wiper will stop on this set of terminals which will cut the 35 lines through to the connector switch and deenergize all of the relays in the manner described for the first -selectors, and to the ground on wiper a, which will, in turn, ground wire 93, which is connected to the switching relay, S of the connector switch (Fig. "5) to battery and ground 2 The subscribers line wires have thus been cut through from the second selector switch to wires 94 and 95 which are connected directly through the operating relay C battery a2 thus energizing the said relay by reason of the fact that the lines are closed at the calling subscribers station. The action of the relay, C energizes the relay, J, as follows: ground a, spring 0, contact 0 wire 96, relay J, battery w, ground 2 thus energizing relay J. When the impulse wheel, 6, (Fig. 1) is operated, relay, will respond and opn and close its contacts, but as relay 'J is a slow relay it will remain in energized condition and a circuit will be established to operate relay L after the off-normal spring, a", breaks contact. It is to be noticed, however, that relay L is energized as soon as relay J operates its springs, as follows: ground 2, spring 0", contact 0, wires 99 and 100, relay L, wire 101, contact 7' spring j wire 102, battery it, to ground 2 thus energizing relay L. Relay N will now be energized by the action of relay J, as follows: ground 2 spring 7' contact 3, wires 97, 105 and 106, relay N, wires 107 and 108, contact Z spring Z battery m to ground 2 thus energizing relay N. After the switch has taken one step the contact between the oif-normal spring, 0 and contact, a, would be broken and relay L would be deenergized, but relay L is a slow relay and will receive impulses from operating relay C as follows: ground 2 spring j", contact j, wires 97 and 98, contact 0 spring 0 wires 109, contact a, spring 41?, wire 110 and 100, relay L, wire 101, contact jfl spring 7' wire 102, battery so, to ground 2. As relay L is a slow relay it will remain in en ergized condition during the time that relay C is receiving impulses. At the same time the motor magnet M is operated, as follows: ground 2 spring 7' contact 7' wires 97 and 98, spring 0, contact 0, wire 111, motor magnet M, wire 112, spring 1' contact 7*, Wires 113 and 108, contact Z spring Z battery m to ground 5 thus completing the circuit to energize motor magnet M. As soon as relay O stops receiving impulses, relays L and N will become deenergized and the circuit through which motor magnet M was energized will be broken so that the switch cannot again be stepped around until after it has been restored to normal position. I will now suppose that wipers, 0 c and 0 have been moved into contact with f contacts, 0 a" and 0 and I have a circuit from ground a, spring '0 contact '0 Wire 1141, contact 72., spring 12., wire 115, wiper moaera 0, contact 0 wires 116 and 117, to relay" D and battery re'lay D is the cut-off relay for the called station A This operates the called subscribers cut-ofi' relay 1), which will thus cut off his line relay to prevent its being operated by the closing of his line, so that the removing of his telephone will .not start the finder switch; also a connection is established from ground .2 to term1- nal contact 0 and to multiples thereof so that if a connector switch should stop on a multiple of this contact it would receive a busy test. The application of the busy test depends upon the operation of relay V. Relay V is energized over a circuit which can be traced from wiper 0 and Wire 115 to contact a on relay N, and thence by way of a front contact on relay N, back contact on relay L and relay T to relay V, battery and ground. This circuit is completed upon the deenergization of relay L and before relay N, which would open this circuit, is deenergized. The relay V, however, would be held up after the opening of said circuit at relay N by a locking circuit over a part of the circuit last described, and passing through c on relay V, wires 105 and 97, and contacts i and 7' to ground at 2 so. that the busy tone would be applied until the switch is released and said holding circuit is broken at contact 7' when relay J is deenergized. It should likewise be noted that relay W is energized as soon as relay L is denergized by means of a circuit traceable from ground a, spring 7' contact j", wires 97, 105 and 121, spring 21 contact a, wire 122, contact 8 spring 8, wire 123, relay W, wire 124, contact Z spring Z battery as, ground a. This station is ready to be rung and this is accomplished by intermittent ringing current and intermittent battery supplied and controlled by a ringing switch, B1 (Fig. 5). This intermittent battery operates relay O, (Fig. 5) as follows: battery w", iper 7 through the bank contacts to wire 118, spring 'w contact w wire 119, contact p spring 79 wire 120 relay 0, to ground .2 thus energizing relay 0.

Generator current is furnished to the called line as follows: brush 1" (Fig. 5), to the contacts of the ringing switch bank wiper r wires 126 and 127, spring w contact w wire 128, contact 0 spring 0 re-r lay 0 being denergized, wire 129, wiper a, contact 0, wires 130 and 131, to one side of the bells 6, through the bells and condenser to wire 132, contact 133, spring 134, wires 135 and 136, contact 0 wiper 0, wire 137, spring 0 contact 0 wire 138, contact 10 spring w, wire 139, brush 1", thus completing the circuit through the bells and generator.

When the receiver is removed from the hook at the called station, A relay T will be energized as follows: from grounded or tive side of the battery, a3 passes through I coil 2?, of relay T, to wires 140 and 141, to contact '0, and when relay 0 isenergized th line is extended to spring 0 wires 137, and so on, as above described, for the ringing circuit to the called station. Thus it can be seen that when the line is closed at the called station, relay T will be energized nd relay 0, having been energized by the battery from the ringing switch, will remain energized as long as relay T is energized, as follows: When relay T is energized it closes a circuit through relay P which can be traced from ground a" through wire 142, contact t spring 2?, wire 143, relay P, battery 00 to ground 2. Thus relay T will operate and close a circuit which in turn willlock the operative relay 0 as long as relay P is energized. This circuit extends from battery a? by way of wire 144, contact 79 spring 72 wire 120, relay 0 to ground 2 Thus the subscribers talking circuit will be closed at the make contacts of relay 0 and this relay will hold the circuit closed until. relay T is deenergized by the opening of the called subscribers loop at the called subscribers telephone set, due to the hanging up of the receiver.

Condensers are interposed between the lines ofthe calling station and the called station, thus comp eting the talking circuit between the two stations. It must now be shown how the release of the switches is accomplished: I will start with the connector switch (Fig. 5) and trace the release back to the finder switch (Fig. 2). When the eall ingparty hangs up his receiver relay C will become deenergized and close the following circuits to energize release relay R and R the deenergizing of relay C opens the circuit for relay J permitting its armature springs j and j to engage back contacts and 4', this closes the circuit for release relay R from ground at 2 contact 8 spring a, wire 147, contact 3', spring 7', wire 148, back contact r,'spring) 1*, wire 149, release magnet R, wire 150, attery as, to ground .2 also as soon as release magnet R is energized the circuit for relay R is as follows: ground a, spring 1' contact wire 145, contactr, spring 1' wire 146,

relayR, battery 40 to ground 2, thusrei lay R can not be energizeduntil after the release magnet is energized and as soon as release relay R is energized the release magnet R is deenergized by breaking its circuit at contact 1.

release the switch in the manner well underp The energizing and deenergizing of the release magnet Rcausesit to 18% stood with the type of switch illustrated in the drawings and hereinafter very briefly described. At the same time that relay R was energized the following circuit was completed to release the second selector: ground a, spring 1", contact 1, wire 152, contact a, wiper a, wires 153 and 154, springr, contact 7-, wire 155, relay R wire 1-56, contact e, spring e battery in, ground 2,

thus energizing relay R which will estabergized, the following circuit was also established to releasethe' first selector and finder switches: ground 2 contact 0 spring c wire 158, spring r", contact 7*, wire 159, spring e, contact a, wire 160, contact a, wiper a, wire 161, wire 162, contact a, spring 6 wire 163, release magnet R wire 164, contact u spring 14 battery so, to ground 2 thus ener izing the first selector release magnet R", which closes the following circuit: ground 2 contact 1', spring 1*, wire 165, finder release magnet R wire 166, contact a spring Q02, battery on, to ground .2 thus energizing release magnet R, which establishes the following circuit to energize locking relay U: ground e, spring 0", contact 1", wires 167 and 168,

locking relay U, to battery m, to ground .2 thus energizing relay U and opening the battery circuit for release magnets R and R at contact u Relay U will remain locked up until the finder switch returns to its normal position, as follows: ground a", spring 6 contact I), wire 36, spring a", contact a", wire 169, contact d spring cl, wires 170 and 168, relay U, battery w, to ground 2 thus closing its own energizing circuit until broken by the off-normal spring 6 It will thus be seenthat means are provided by which calls may be automatically interchanged between any desired number of subscribers by a number of switches which will be governed almost entirely by the amount of trailic. The use of the intermediate finder switches in connection with the selector switches, which has heretofore been the practice when the flat or one movement switches, are employed, is entirely dispensed with, the selector switches being adapted, when a group is found, to automatically select an idle trunk in the group.

In the, selector switch I have shown two relays, B and B for operating the four spring contacts in connection with the circuits described. It is obvious that one relay might be used to perform this function by supplying its armature with the four contacting devices. This same is true of the relays D and E which are connected in multiple to wire 57 and through battery to ground. I have shown the two relays in each case, for this purpose, as connections are more simple than where four switching contacts are supplied to one relay.

The dead contacts are to prevent the switch from stepping past agroup in case all the trunks in the group are busy. In such case the switch would stop when it reached the dead contact. Means (not shown) would also be provided for auto matically releasing the switch in this event. The switches which are employed are not materially different from those employed by Lattig and Groodrum and as set forth in previous applications filed by myself. Fig. 9 shows a plan view of the switch, M being the motor magnet and R the release magnet, M is the operating pawl attached to the armature h 2 of the motor magnet. An arm, R attached to the armature R of the release magnet and having an olf-set portion R at the top, as shown in Fig. 13, to engage the operating pawl when the magnet is energized and thus draw the operating pawl and the holding pawl M out of contact with the ratcheted wheel M by means of the spring B when the release magnet is deenerglzed. The wipers which are operated by the ratcheted wheel M are shown at M*, M and M to engage with the bank contacts arranged in horizontal rows, as shown at M, M and M in Fig. 11. Off-normal spring for operating the off-normal contacts when the switch is started is shown at M, and.

coil spring M arranged in a spring case attached to the shaft is adapted to return the wipers to normal position when released.

It is quite obvious that the particular form of the switches used forms no part of the invention and that same might be used with switches of various kinds and that the con structions and arrangements might be variously changed and not affect the spirit of the invention.

Having thus described my invention, I claim:

1. In an automatic telephone exchange, a series of finder switches, and means for operating said switches to find a subscribers I line by closing the subscribers circuit, selector switches connected to said finder switches, means for operating said selector switches in response to interruptions in the current passing over the subscribers line to cause said'selector switch to step any desired distance, trunks having terminal contacts in said selector switches arranged in groups, said trunks being connected in mul tiple to other selector switches and means for continuing the operation of a switch after the impulses from the subscribers station have ceased to cause it to automatically find an idle trunk in the group selected.

2. The combination with a selector switch having bank terminal contacts arranged in groups in the same horizontal plane, wipers or traversing said contacts, and an operating relay connected with said switch adapted to be connected to a subscribers line and respond to impulses from a subscribers station, a motor magnet controlled by said operating relay to cause said switch to advance one step for each impulse in said operatingrelay, and a second opera-ting relay adapted to receive operative energy through a circuit in which a Wiper on said switch constitutes a part, said second operating relay being adapted to control said motor magnet and operate the same when the wiper on said switch completes the circuit to said second operative relay, and means for completing the circuit through said wiper when a trunk associated with the terminal with which said wiper is engaged is in use in another switch, as and for the purpose set forth.

3. In an automatic telephone system, se-

lector switches, terminal contacts arranged in horizontal rows, means for operating said switches by impulses from the subscribers station to cause the wipers of a switch to traverse said terminal contacts, and means for supplying current to the operatim mechanism of a switch through one of said contacts to cause it to continue its operation to find an idle trunk or connection, and means for holding the operating mechanism of said switch from being released by the opening of the subscribers line during the automatic stepping of said switch, as and for the purpose set forth.

, 4. In an automatic telephone system, a series of subscribers lines, finder switches less than the number of lines arranged in groups and connected in multiple to. said lines, a plurality of selector switches less than the number of lines and connected to said finder switches, connector switches arranged in groups connected in multiple to trunks terminating in contacts arranged in groups in the selector switches, said contacts in different switches being arranged in single banks but the groups separated by abnormal contacts, means in said selector switches for responding to impulses from the subscribers station when connected thereto by the finder switches, said impulses thereby being adapted to cause said selector switches to move one step for each impulse to select the terminals of trunks in different groups, and means for automatically continuing the operation of said switch after said impulses cease to cause it to find an idle trunk in the said group and to connect the subscribers wires to the said idle trunk and thus to a connector switch, said abnormal contacts being arranged to automatically stop said switch and prevent its further mm'ement in case all the trunks of the group are busy, as and for the purpose set forth.

In an automatic telephone exchange a selector switch and other switches with which the subscribers lines are to be conranged in groups to said other switches,

said trunk connections ending in terminals arranged in groups in banks of said selector switch, an operating relay independent of said line relay adapted to be operated by current supply through a circuit of which one of the terminals of said trunk is a part, means connected with said operating relay for causing the motor magnet to respond to impulses in said operating relay independent of said line relay, means for deenergizing said operating relay and thusstopping said switch when the wiper reaches an idle trunk, and electrical means also operated through said .wiper'to disconnect the line relay and to switch the subscribers lines onto the wipers of the switch for connection to the idle trunk thus found.

6. In an automatic exchange havinga selector switch, a line relay, means for connecting said line relay onto subscribers lines, a motor magnet adapted to produce a stepby-step movement of said switch in response to impulses to said line relay, an operating relay independent of said line relay normally connected to a wiper in said switch and adapted to be operated by current supplied through a circuit of which one of the bank terminals of the switch is a part, and a slow relay adapted to receive impulses simultaneously with the impulses of the motor magnet to open the circuit of the operating relay while said motor magnet is be: ing operated from said line relay, said operating relay being adapted when energized to operate said motor magnet.

7. In a telephone systennaselector switch, a line relay, a switching relay for switching the subscribers line through said line relay and a circuit including a motor magnet by which impulses in the line relay are repeated into said motor magnet, a slow relay also energized by the operation of said line relay to close the circuit of the motor magnet, an operating relay independent of said line relay adapted under certain conditions to receive current through a circuit formed in part by the wiper of said switch and when energized to operate said motor 1 $103,572 I maghefle -seconds1ow' ,pelay energized by" the current is flowifig unint erruptedly the opposite movement of the 'lineflel'ay thfbugh' said line'frehy. 18

I armature from that which energizes' the j ,In tes'tl'mdnfy whereof, I have hereunto set 5 ing adapted to open, the circuit from the I v l-wiper to saidoperating relay when 'en'er-" Witnesses day of May 1909.

first slow relay, said'secoiid low re1a'y.bemy hand "this 18th BERT DLTNHAM.

i 'zed by impulses repeated thereto from the CHAS. LWEL H,

inei'elay and to become deinergizd when MARJQRIE S. MOR W 7 copies ot'thh patent may be obtained or he cents each, by agltigehihfi the "l Gominis'sieneh-ot Patents, v wum'n pognq," 

